IS 3400 (Part 2) :2003 ISO 48:1994

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Indian Standard

METHODS OF TEST FOR VULCANIZED

RUBBER
OF

PART 2 RUBBER, VULCANIZED OR THERMOPLASTIC-- DETERMINATION HARDNESS (HARDNESS BETWEEN lb lf%H-D AND 100 IRHD) , . ~.

(Third Revkion )
ICS 83.060

@ BIS 2003

BUREAU
MANAK

OF
BHAVAN,

INDIAN

STANDARDS
ZAFAR MARG

9 BAHADUR SHAH NEW DELHI 110002

April 2003

Price Group

7

Rubber and Rubber Products

Sectional Committee,

PCO 13

NATIONAL FOREWORD This Indian Standard (Part 2) (Third Revision) which is identical with ISO 48:1994 `Rubber, vulcanized thermoplastic -- Determination of hardness (hardness between 10 IRHD and 100 IRHD)' issued by International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards the recommendations of the Rubber and Rubber Products Sectional Committee and approval of Petroleum, Coal and Related Products Division Council. or the on the

This standard was first published in 1965 and revised in 1980 which included the testing of thin pieces of rubber by a scaled-down version (micro-test) of the normal test piece aligned with ISO 48:1987. In second revision, in 1995, the hardness test specified was intended to provide a rapid measurement of rubber stiffness, unlike hardness test on other materials which measure resistance to permanent deformation or to obtain. The Committee, therefore, decided to revise this standard to completely align with ISO 48:1994. The text of ISO Standard has been proposed to be approved as suitable for publication as Indian Standard without deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly a) b) drawn to the following: Standard' appear referring to this standard, they should

Wherever the words `International be read as `Indian Standard'.

Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker.

In this adopted standard, reference appears to certain International Standards for which Indian Standards also exist. The corresponding Indian Standards which are to be substituted in their place are listed below along with their degree of equivalence for the editions indicated. However, that International SEindard cross-referred in this adopted ISO Standard which has subsequently been revised, position in respect of latest ISO Standard has been given: International Standard Corresponding Indian Standard Degree of Equivalence Technically equivalent with minor deviation --

1S0 471 :') Rubber--Times, temperatures and humidities for conditioning and testing

standard IS 13867 : 1993 Rubber temperatures, humidities and times for the conditioning and time interval between vulcanization and testing of test pieces Nil

ISO 1826 : 1981 Rubber, vulcanized--Time-interval between vulcanization and testing-- Specification ISO 3383 : 1985 Rubber-- General directions for achieving elevated or subnormal temperatures for test purposes ISO 4661-1 : 1993 Rubber, vulcanized or thermoplastic -- Preparation of samples and test pieces -- Part 1 : Physical tests lSOflR 9272:1986 Rubber and rubber products -- Determination of precision for test method standards 1)TObe published (Revision of IS 471:1983).

-- Nil

Nil

--

Nil

--

(Continued

on third cover)

IS 3400 (Part 2) :2003 ISO 48:1994

Indian Standard

METHODS OF TEST FOR VULCANIZED
PART 2 RUBBER, HARDNESS VULCANIZED (HARDNESS OR THERMOPLASTIC-- BETWEEN 10 IRHD AND

RUBBER
OF

DETERMINATION 100 IRHD)

( Third Revision)

1

Scope

This International Standard specifies four methods for the determination of the hardness of vulcanized or thermoplastic rubbers on flat surfaces: Method N Method Method Method H L M Normal test High-hardness Low-hardness Microtest test test

than or equal to 4 mm and is preferably used for rubbers in the range 35 IRHD to 85 IRHD but may be used for those in the range 30 IRHD to 95 IRHD. Method H: The appropriate method for test pieces of thickness greater than or equal to 4 mm and hardness in the range 85 IRHD to 100 IRHD. Method L: The appropriate method for test pieces of thickness greater than or equal to 6 mm and hardness in the range 10 IRHD to 35 IRHD. NOTE 1 The value of hardness obtained by method N within the ranges 85 IRHD to 95 IRHD and 30 IRHD to 35 IRHD may not agree precisely with that obtained using method H or method L, respectively. The difference is not normally significant for technical purposes. Method M: The microtest for hardness is essentially a scaled-down version of the normal test method N, permitting the testing of thinner and smaller test pieces. It is the appropriate method for test pieces of thickness less than 4 mm and is preferably used for rubbers in the range 35 IRHD to 85 IRHD but may be used for those in the range 30 IRHD to 95 IRHD.

and four methods for the determination of apparent hardness of curved surfaces using methods N, H, L and M, respectively: Methods CN, CH, CL and CM.

The methods differ primarily in the diameter of the indenting ball and the magnitude of the indenting force, these being chosen to suit the particular application. The range of applicability of each is indicated in figure 1. Method N: The normal test for hardness is the appropriate method for test pieces of thickness greater

H!gh

t-

i

IRHD 0 10

d--+-----1
30 35 50 85 95 100

Figure 1 -- Range of applkabilhy

IS ISO

3400

(Part 2) :2003

48:1994

NOTE 2 Because of various surface effects in the rubber and of any slight surface roughness (produced, for example, by buffing), the microtest will not always give results agreeing with those obtained by the normal test, Methods CN, CH, CL and CM: Apparent-hardness tests on curved surfaces. These methods are modifications of methods N, H, L and M for cases where the rubber surface tested is curved. Two cases exist, depending whether a) the test piece or article tested is large enough for the hardness instrument to rest upon it; it is small enough for both the test piece and the instrument to rest upon a common support.

ISO 4661-1:1993, Rubber, vu/c&?ked or thi?mnop/astic -- Preparation of samples and test pieces -- Part 1: Physical tests. lSO/TR 9272:1986, Rubber and rubber products -- Determination of precision for test method standards.

3

Principle

b)

A variant of b) would be where the test piece rests on the specimen table of the instrument. The procedures described cannot provide for all possible shapes and dimensions of test pieces but cover some of the commonest types such as "O" rings, Determination of the apparent hardness of rubber-covered rollers is dealt with separately in ISO 7267-1:1986, Rubber-covered rollers -- Determination of apparent hardness -- Part 1.. IRHD method, ISO 7267-2:1986, Rubber-covered rollers -- Determination of apparent hardness -- Part 2: Shore-type durometer method and ISO 7267-3:1988, Rubber-covered rollers -- Determination of apparent hardness -- Part 3: Pusey and Jones method.

The hardness test consists in measuring the difference between the depths of indentation of a ball into the rubber under a small contact force and a large total force. From this difference, multiplied when using the microtest by the scale factor 6, the hardness in international rubber hardness degrees (IRHD) is obtained by using tables 3 to 5 or on graphs based on these tables or a scale, reading directly in international rubber hardness degrees, calculated from the tables and fitted to the indentation-measuring instrument. These tables and curves are derived from the empirical relationship between indentation depth and hardness given in annex A.

4

Definitions
Standard, the

For the purposes of this International following definitions apply.

2

Normative

references

The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 471 :--1}, Rubber -- Times, temperatures midities for conditioning and testing. and hu-

4.1 international rubber hardness degrees (IRHD): A hardness scale chosen so that "O" represents the hardness of material having a Young's modulus of zero and "100" represents the hardness of a material of infinite Young's modulus, with the following conditions being fulfilled over m'ost of the normal range of hardness: a) one international rubber hardness degree always represents approximately the same proportionate difference in the Young's modulus; for highly elastic rubbers, the scales of IRHD and the Shore A durometer are comparable.

b)

ISO 1826:1981, Rubber, vukanized -- Time-interva/ between vulcanization and testing -- Specification. ISO 3383:1985, Rubber -- General directions for achieving elevated or subnormal temperatures for test purposes, 1) To be published. (Revision of ISO 471 :1983)

4.2 standard hardness (denoted by the letter S): The hardness, reported to the nearest whole number in international rubber hardness degrees, obtained using the procedures described in methods N, H, L and M on test pieces of the standard thickness and not less than the minimum lateral dimensions specified. 4.3 the apparent hardness: The hardness, reported to nearest whole number in international rubber

2

IS

3400

(Part 2) :2003

ISO 48:1994

hardness degrees, obtained using the procedures described in methods N, H, L and M on test pieces of non-standard dimensions, as well as hardness values obtained using methods CN, CH, CL and CM, NOTE 3 Values obtained by methods CN, CH, CL and CM are always given as apparent hardness since tests are commonly made on the complete article where the thickness of the rubber will vary, and in many cases the lateral dimensions will not provide the minimum distance between the indentor and the edge necessary to eliminate edge effects. the readings obtained therefore do not in general coincide with readings obtained on standard test pieces as defined in methods N, H, L and M or on a flat parallel-faced slab of, the same thickness as the article. Moreover, the readings may depend appreciably on the method of support of the article and whether or not a presser foot is used. It should, therefore, be recognized that results obtained on curved surfaces are arbitrary values applicable only to test pieces or articles of one particular shape and of particular dimensions, and supported in one particular way, and in extreme cases such values may differ from the standard hardness by as much as 10 IRHD. Furthermore, surfaces that have been buffed or otherwise prepared to remove cloth markings, etc., will give slightly different hardness values from those with a smooth, moulded finish.

5.1.1 Vertical plunger, having a rigid ball or spherical surface on the lower end, and means for supporting the plunger so that the spherical tip is kept slightly above the surface of the annular foot prior to applying the contact force.

5.1.2 Maans for applying a contact force and an additional indenting force to the plunger, making allowance for the mass of the plunger, including any fittings attached to it, and for the force of any spring acting on it, so that the forces actually transmitted through the spherical end of the plunger are as specified.

5
5.1

Apparatus
Methods N, H, L and M

5.1.3 Means for measuring the. incraase in depth of indentation of the plunger caused by the indenting force, either in metric units or reading directly in IRHD. The means employed may be mechanical, optical or electrical.

The essential parts of the apparatus are as follows, the appropriate dimensions and forces being shown in table 1.

Table 1 -- Forces and dimensions of armaratus Diameters Test mm Method N (normal test) Method H Ball 2,50 + 0,01 Foot 20 A 1 Hole 6 + 1 Contact N
1

Forceon bell Indenting N 5,40 * 0,01

Total N 5,70 * 0803

Forceon foot N 8,3 * 1,5

0,30 * 0,02

I

(high hardness) Method L (low hardness) Method M (microtest)

I

Ball 1,00 A 0,01 Foot 20 + 1 Hole 6 + 1 Ball 5,00 * 0,01 Foot 22 + 1 Hole lO+l mm

0,30 * 0,02

5,40 * 0,01

5,70 * 0,03

8,3 * 1,5

I
0,30 * 0,02 mN 8,3 * 0,5

I
5,40 * 0,01 mN 145 * 0,5

I
5,70 * 0,03 8,3 * 1,5 mN 153,3 * 1,0 mN 235 & 30

I

Ball 0,395 ~ 0,005 Foot 3,35 + 0,15 Hole 1,00 + 0,15

I

I

I

3

IS ISO

3400 48:

(Part 2) :2003 1994

5.1.4 Flat annular foot, normal to the axis of the plunger and having a central hole for the passage of the plunger. The foot rests on the test piece and exerts a pressure on it of 30 kPa * 5 kPa2) provided that the total load on the foot does not fall outside the values given in table 1. The foot shall be rigidly connected to the indentation-measuring device, so that a measurement is made of the movement of the plunger relative to the foot (i.e. the top surface of the test piece, not relative to the surface supporting the test piece). 5.1.5 Means for gently vibrating the apparatus, for example an electrically operated buzzer, to overcome any slight friction. (This may be omitted in instruments where friction is completely eliminated.) 5.1.6 Chamber for the test piece, when tests are made at temperatures other than a standard temperature. This chamber shall be equipped with a means of maintaining the temperature within 2 "C of the desired value. The foot and vertical plunger shall extend through the top of the chamber, and the portion passing through the top shall be constructed from a material having a low thermal conductivity. A sensing device shall be located within the chamber near or at the location of the test piece, for measuring the temperature (see ISO 3383). In the microtest when using instruments in which the test piece table is pressed upwards by a spring, the values of the foot pressure and the force on the foot are those acting during the period of application of the total force. Before the indenting force of 145 mN is applied, the force on the foot is greater by this amount, and hence equals 380 mN * 30 mN. NOTE 4 Not all possible combinations of dimensions and forces in table 1 will meet the pressure requirements of 5.1.4.

the base. The diameter of the cylinders and their distance apatt shall be such as to locate and support the instrument on the curved surface to be tested. Alternatively, the modified base may be fitted with feet movable in universal joints so that they adapt themselves to the curved surface. 5.2.2 Surfaces with double curvature of large radius greater than 50 mm The instrument shall be used, specified in 5.2.1 with adjustable feet

5.2.3 Cylindrical surfaces of radius 50 mm or small test pieces with double

4 mm to curvature

On surfaces too small to support the instrument, the test piece or article shall be supported by means of special jigs or V blocks so that the indentor is vertically above the test surface. Wax may be used to fix small items to the test piece table. NOTES 5 In generai, an instrument as described for method M should be used only where the thickness of the rubber tested is less than 4 mm. 6 Instruments for method M in which the test piece table is pressed upwards by a spring are not suitable for use on large test pieces or articles with a large radius of curvature. 5.2.4 Small "O" rings and curvature less than 4 mm articles of radius of

These shall be held in suitable jigs or blocks or secured by wax to the instrument table. Measurements shall be made using the instrument for method M. No test shall be made if the smallest radius is less than 0,8 mm.

5.2

Methods

CN, CH, CL and CM

6

Test pieces
shall be prepared in accordance with

The apparatus used shall be essentially that described in 5.1 but differing in the following respects. 5.2.1 Cylindrical surfaces of radius greater than 50 mm The base of the instrument shall have a hole below the plunger, allowing free passage of the annular foot such that measurement may be made above or below the base. The lower surface of the base shall be in the form of two cylinders parallel to each other and the plane of 2) 1 kPa = 103 N/mz

Test pieces ISO 4661-1.

6.1 6.1.1

Methods N, H, L and M
General

The test pieces shall have their upper and lower surfaces flat, smooth and parallel to one another. Tests intended to be comparable test pieces of the same thickness. shall be made on

4

IS ISO

3400

(Part 2) :2003

48:1994

6.1.2

Thickness

6.1.3.2

Method M

6.1.2.1

Methods N and H

The lateral dimensions shall be such that no test is made at a distance from the edge of less than 2 mm. When test pieces thicker than 4 mm are tested on the microtest instrument because the lateral dimensions or the available flat area do not permit testing on a normal instrument, the test shall be made at a distance from the edge as great as possible.

The standard test piece shall be 8 mm to 10 mm thick and shall be made up of one, two or three layers of rubber, the thinnest of which shall not be less than 2 mm thick. All surfaces shall be flat and parallel. Non-standard test pieces may be either thicker or thinner but not less than 4 mm thick.

6.1.2.2 Method L The standard test piece shall be 10 mm to 15 mm thick and shall be made up of one, two or three layers of rubber, the thinnest of which shall not be less than 2 mm thick. All surfaces shall be flat and parallel. Non-standafd test pieces may be either thicker or thinner but not less than 6 mm thick.

6.2

Methods

CN, CH, CL and CM

6.1.2.3

Method M

The test piece shall be either a complete article or a piece cut therefrom. The underside of a cut piece shall be such that it can be properly supported during the hardness test. If the surface on which the test is to be made is cloth-marked, it shall be buffed prior to testing. Test pieces shall be allowed to recover at a standard temperature (see ISO 471) for at least 16 h after buffing and shall be conditioned in accordance with clause 8. The conditioning period may form part of the recove~ period.

The standard test piece shall have a thickness of 2 mm i 0,5 mm. Thicker or thinner test pieces may be used, but in no case less than 1 mm thick. On such test pieces, the readings will not in general agree with those obtained on the standard test piece.

7 Time-interval and testing

between

vulcanization

6.1.3

Lateral dimensions

Unless otherwise specified for technical reasons, the following requirements shall be observed (see ISO 1826). For all normal test purposes, the minimum time between vulcanization and testing shall be 16 h. In cases of arbitration, the minimum time shall be 72 h. For non-product tests, the maximum time between vulcanization and testing shall be 4 weeks and, for evaluations intended to be comparable, the tests, as far as possible, shall be caTried out after the same time-interval. For product tests, whenever possible, the time between vulcanization and testing shall not exceed 3 months. In other cases, tests shall be made within 2 months of the date of receipt by the purchaser of the product.

6.1.3.1 Methods N, H and L The lateral dimensions of both standard and nonstandard test pieces shall be such that no test is made at a distance from the edge of the test piece less than the appropriate distance shown in table 2.

Table 2 -- Minimum distance of point of contac from test piece edga
Dimensions in millimetrc

Total thickness piece

of test

Minimum distance from point of contact to edge of test piece 7,0 8,0

4 6 8

8

Conditioning

of test pieces

9,0 10,0
11,5 13,0

10
15 25

8.1 When a test is made at a standard temperature (see ISO 471), the test pieces shall be maintained at the conditions of test for at least 3 h immediately before testing.

5

IS 3400 (Part 2) :2003

1s0

48:1994

8.2 When tests are made at higher or lower temperatures, the test pieces shall be maintained at the conditions of test for a period of time sufficient to reach temperature equilibrium with the testing environment, or for the period of time required by the specification covering the material or product being tested, and then immediately tested.

ments in international rubber hardness degrees cated by the degree sign 0, followed by

(indi-

a)

either the letter S for the standard test piece thickness or the thickness and smallest lateral dimension (in millimetres) for tests on non-standard test pieces (the result then being an apparent hardness); the code-letter for the method, i.e. N for normal test, H for high, L for low and M for microtest; for tests on curved surfaces, the prefix letter C

9

Temperature

of test

b)

The test shall normally be carried out at standard temperature (see ISO 471). When other temperatures are used, these shall be selected from the list of preferred temperatures as specified in ISO 471.

c)

13
10

Precision
General

Procedure
13.1

Condition the test piece as specified in clause 8. Lightly dust the upper and lower surfaces of the test piece with dusting powder. Place the test piece on a horizontal rigid surface, Bring the foot into contact with the surface of the test piece. Press the plunger and indenting ball for 5 s on to the rubber, the force on the ball being the contact force. If the gauge is graduated in international rubber hardness degrees (IRHD), it shall be adjusted to read 100 at the end of the 5 s period; the additional indenting force shall be then be applied and maintained for 30 s, when a direct reading of the hardness in international rubber hardness degrees is obtained, If the gauge is graduated in metric units, the differential indentation D (in hundredths of a millimetre) of the plunger caused by the additional indenting force, applied for 30 s, shall be noted. This (after multiplying by the scale factor of 6 when using the apparatus for the microtest) shall be converted into international rubber hardness degrees by using tables 3 to 5 or a graph constructed therefrom. During the loading periods, the apparatus shall be gently vibrated unless it is completely free of friction.

The precision calculations to provide repeatability and reproducibility values were performed in accordance with lSO/TR 9272. Consult this for precision concepts and nomenclature. Annex B gives guidance on the use of repeatability and reproducibility values.

13.2

Programme f

details

13.2.1 Five interlaboratory test programmed (ITPs) conducted by Statens were and organized Provningsanstalt (Sweden) between 1985 and 1989. Cured test pieces were prepared in one laboratory and sent to all the participants. The details of the five ITPs are as follows: Medium-hardness rubbers, method N: Four rubber compounds, nominal hardness range 30 IRHD to 85 IRHD, 26 laboratories. Three determinations (measurements) of hardness on each compound on each of two days, one week apar?, using method N. The median of the three used as the "test result" for the precision analysis. Mediurn-hardness rubbers, method M: Four rubber compounds, nominal hardness range 30 IRHD to 85 IRHD, 26 laboratories. Three determinations (measurements) of hardness on each of two days, one week apart, using method M. The median of the three used as the "test result" for the precision analysis. High-hardness rubbers, method N: Three rubber compounds, nominal hardness range 85 IRHD to 100 IRHD, 12 laboratories. Five determinations (measurements) of hardness on each of two days, one week apart, using method N. The median of the five used as the "test result" for the precision analysis.

11

Number of readings

One measurement shall be made at a minimum of three different points distributed over the test piece and the median of the results shall be taken, i.e. the middle value when these are arranged in increasing order,

12

Expression of results

Hardness shall be expressed to the nearest whole number as the median of the individual measure-

6

IS

3400

(Part 2) :2003

1s0

48:1994

High-hardness rubbers, method H: Three rubber compounds, nominal hardness range 85 IRHD to 100 IRHD, 12 laboratories. Three determinations (measurements) of hardness on each of two days, one week apart, using method H. The median of the three used as the "test result" for the precision analysis. Low-hardness rubber, method L: One rubber compound of nominal low hardness, five laboratories. Three determinations (measurements) of hardness on each of two days, one week apart, using method L, The median of the three used as the "test result" for the precision analysis.

The symbols r, (r), R and (R) as used in the table of results are defined as follows:

r = absolute repeatability,
(r) = relative repeatability, R = absolute units;

in measurement in percent; in

units;

reproducibility,

measurement

(R) = relative reproducibility,

in percent.

14

Test repoti
particulars:

The test report shall include the following 13.2.2 The precision assessments are type 1 (cured, prepared test pieces circulated) and the time for repeatability and reproducibility is on a scale of days. For the low-hardness rubber, method L, due to the small number of laboratories in the precision evaluation programme, the tcbulated precision results should be used with caution. a) a reference to this International method used;

Standard and the

b)

the form of the test piece, the number of layers and the dimensions of the thinnest layer plus, ii? the case of curved or irregularly shaped test pieces, the test piece description, the method of mounting and the method of applying the test force; the temperature of test; i.e. moulded, buffed

13.3

Precision results

c) d)

The precision results are given in table6 for mediumhardness rubbers using method N, table 7 for medium-hardness rubbers using method M, table 8 for high-hardness rubbers using method N, table9 for high-hardness rubbers using method H, and table 10 for the low-hardness rubber using method L,

the type of surface tested, or other: the hardness, expressed

e) f)

as in clause

12;

any deviation from the procedure

specified.

7

IS 3400 (Part 2) :2003 ISO 48:1994

Table 3 -- Conversion of values of D to international rubber hardness degrees (IRHD) for use in method N D = differential indentation, in hundreths of a millimetre, with 2,5 mm indentor D
o IRHD 100,0

D
46 47 48 49 50 51 52 53 54 55

IRHD 73,3 72,7 72,2 71,6 71,0 70,4 69,8 69,3 68,7 68,2

D
92 93 94 95 96 97 98 99 100 101

IRHD 51,6 51,2 50,9 50,5 50,2 49,8 49,5 49,1 48,8 48,5

D
138 :39 140 141 142 143 144 145 146 147

IRHD

38,2
38,0 37,8 37,5 37,3 37,1 36,9 36,7 36,5 36,2

1
2 3 4 5 6 7 8 9 10

100,0
99,9 99,8 99,6 99,3 99,0 98,6 98,1 97,7

11 12 13
14

97,1 96,5 95,9 95,3
94$7

56 57 58 59
60

67,6 67,1 66,6 66,0
65,5

102 103 104 105
106

48,1 47,8 47,5 47,1
46,8 46,5 46,2 45,9 45,6 4583 45,0 44,7 44,4 44,1 43,8 43,5 43,3 43,0 42,7 42,5 42,2 41,9 41,7 41,4 41,1 40,9 40,6 40,4 40,1 39,9 39,6 39,4 39,1 38,9 38,7 38,4

148 149 150
151

36,0 35,8 35,6
35,4

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

94,0 93,4 92,7 92,0 91,3 90,6 89,8 89,2 88,5 87,8 87,1 86,4 85,7 85,0 84,3 83,6 82,9 82,2 81,5 80,9 80,2 79,5 78,9 78,2 77,6 77,0 76,4 75,8 75,2 74,5 73$9

61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91

65,0 64,5 64,0 63,5 63,0 62,5 62,0 61,5 61,1 60,6 60,1 59,7 59,2 58,8 58,3 57,9 57<5 57,0 56,6 56,2 55,8 55,4 55,0 54,6 54,2 53,8 53,4 53,0 52,7 52,3 52,0

107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137

152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180

35,2 35,0 34,8 34,6 34,4 34,2 34,0 33,8 33,6 33,4 33,2 33,0 32,8 32,6 32,4 32,3 32,1 31,9 31,7 31,6 31,4 31,2 31,1 30,9 30,7 30,5 30,4 30,2 30,0

8

IS 3400 (Part 2) :2003 ISO 48:1994

Table 4 -- Conversion of values of D into international rubber hardness degrees (IRHD) for use in method H D = differential indentation, in hundreths of a millimetre, with 1 mm indentor
D

IRHD 100,0 100,0 100,0 99,9 99,9 99,8 99,6 99,5 99,3 99,1 98,8 98,6 98,3 98,0 97,6

D

IRHD 97,3 97,0 96,6 96,2 95,8 95,4 95,0 94,6 94,2 93,8 93,4 92,9 92,5 92,0 91,6

D

IRHD 91,1 90,7 90,2 89,7 89,3 88,8 88,4 87,9 87)5 87,0 86,6 86,1 85,7 85,3 84,8

o 1 2 3 4 5 6 7 8 9 10 11 12 13 14

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

30 31 32 33 34 35 36 37 38 39 40 41 42 43 44

Table 5 -- Conversion of values of D into international rubber hardness degrees (IRHD) for use in method L D = differential indentation, in hundreths of a millimetre, with 5 mm indentor
D

IRHD 34,9 34,4 33,9 33,4 32,9 32,4 31,9 31,4 30,9 30,4 30,0 29,6 29,2 28,8 28,4 28,0 27,6 27,2 26,8 26,4 26,1 25,7 25,4 25,0 24,7 24,4 24,1 23,a 23,5 23,1 22,8 22,5 22,2 21,9 21,6

D
180 182 184 186 188 190 192 194 196 198 200 202 204 206 208 210 212 214 216 218 220 222 224 226 228 230 232 234 236 238 240 242 244 246 248

IRHD 21,3 21,1 20,8 20,6 20,3 20,1 19,8 19,6 19,4 19,2 18,9 18,7 18,5 18,3 18,0 17,8 17,6 1784 17,2 17,0 16,8 16,6 16,4 16,2 16,0 15,8 15,6 15<4 15,3 15,1 14,9 14,8 14,6 14,4 14,3

D

IRHD 14,1 14,0 13,8 13,7 13,5 13,4 13,3 13,1 13,0 12,8 12,7 12,6 12,5 12,3 12,2 12,1 12,0 11,8 11,7 11,6 11,5 11,4 11,3 11,2 11,1 11,0 10,9 10,8 10,6 10,5 10,4 10,3 10,2 10,1 9,9

110 112 114 116 118 120 122 124 126 128 130 132 134 136 138 140 142 144 146 148 150 152 154 156 158 160 162 164 166 168 170 172 174 176 178

250 252 254 256 25a 260 262 264 266 268 270 272 274 276 278 280 282 284 2a6 288 290 292 294 296 298 300 302 304 306 308 310 312 314 316 318

9

IS ISO

3400

(Part 2) :2003

48:1994

1
Material

Table 6 -- Type 1 precision, medium-hardness rubbers, method N 1
Within Average valua r (r)
4,08 2,61 2,48 2,68

d
labs

lab

Between

R
2,98 2,68 4,47 3,49

(R)
9,47 5,68 6,71 4,03

A B c D
Pooled values

31,5 47,1 66,6 86,5

1,29 1,23 1,65 2,32

58,3

1,68

2,89

3,49

I

5,99

I

Table 7 -- Type 1 precision, medium-hardness rubbers, method M Within lab Material Averagevalue
r (r)

Betweenlabs R 5,82
5,44 7,47

(R) 15,9
10,7 11,5

A
B

36,6
50<9 64,9

1,57
2,31 4,89

4,29
4,55 7854

c
D

88,6
60,3

4,76
3,71

5,38
6,16

6,80
6,43

7,68
10,7

Pooled values

I Material

I

Table 8 -- Type 1 precision, high-hardness rubbers, method N I I Within lab Betweenlabs Averagevaiue r (r) (R) R 85,8 93,4 98,5 0,78 1,11 0,33
I 0,81 I

A B c
I Pcmled values I

0,91 1,19 0.34
0,87 I

3,53 2,96 1.45
2,86 I

4,11 3,17 1.47
3,09

92,6

Table 9 -- Type 1 precision, high-hardness rubbers, method H i Material
I I
I 1

Within lab Averagevalue
r (r)

Betweeniabs R 3,12 2,15 1,03
2,29

(R) 3,41 2,31 1,10
2,46

A B c
Pooied values

87,0 94,2 98,7
93,3

0,96 1,00 0,71
0,75

1,03 1,07 0,76
0,90

10

IS 3400 (Part 21:2003 ISO 48:1994

) Material

1

Table 10 -- Type 1 precision, low-hardness rubber, method L r 1 Within lab ~etweenlabs Averagevalue (R) (r) R r 33,0 0,20 0,61 2,00 6,04

A

;1

IS ISO

3400

(Part

2) :2003

48:1994

Annex

A

(normative)
Empirical relationship between indentation
r b)

and hardness

The relationship between the differential indentation and the hardness expressed in international rubber hardness degrees is based on a) the known relationship, for a perfectly elastic isotropic material, between indentation D, expressed in millimetres, and Young's modulus E, expressed in megapascals, viz: ~ where F is the indenting force, in newtons, = 0,0038 rO'65x D' '35

is the radius of the ball, in millimetres;

the use of a probit (integrated normal error) curve to relate loglJ? to the hardness in international rubber hardness degrees, as shown in figures Al, A.2 and A.3. This curve is defined in terms of 1) the value of logl# corresponding to the midpoint of the curve: 0,364 (E being expressed in megapascals), the maximum slope: crease in logl@ 57' IRHD per unit in-

2)

97,8 92,6 87,6 In g h g w ~ g k c k g 2 G c .9 ~ c k! ~ 81,2 72,9

100 90 80 70

63,4 60 51,7 40,6 29,8 20,9 50 40. 30 20 10 0 1,0

8,6 3,1

7,4
loglo[

7,8

0,2

0,6

1,0

1,4

1,8

( E expressed

in megapascals)

Figure A.1 -- Relationship between Iogl# and hardness in IRHD from 3 to 100

12

IS 3400 (Part 2) :2003 ISO 48:1994

40

30

7

20

--
10

.
1

i,o

0 7,8 0 in megapascals) 0,2

3,2 ; loglo E ( E expressed

Figure A.2 -- Relationship between logl# and hardness in IRHD from 3 to 40

loglof

( f expressed

in megapascals)

Figure A.3 -- Relationship between logl#

and hardness in IRHD from 80 to 100

13

IS

3400

(Part 2) :2003

ISO 48:1994

Annex

B

(informative)
Guidance for using precision results

6.1 The general procedure for using precision results is as follows, with the symbol Ixl ­ ~ I designating a positive difference in any two measurement values (i.e. without regard to sign). B.2 Enter the appropriate precision table (for whatever test parameter is being considered) at an average value (of the measured parameter) nearest to the "test" data average under consideration. This line will give the applicable r, (r), R or (R) for use in the decision process. B.3 With these r and (r) values, the following general repeatability statements may be used to make decisions.
B.3.1
For

between two test values, found on nominally identical material samples under normal and correct operation of the test procedure, will exceed the tabulated repeatability (r) on average not more than once in twenty cases.

B.4'
general

kMth theee

R and

(R) values,
may

the be

following used to

rep~oducibility

statements

make dec~lons.

an absolute

difference:

The difference

B.4.I For an absolute difference: The absolute difference Ixl ­ z I between two independently measured test (v'aiue)' averages, foui'fd in two laboratories using normal and correct test procedures on nominally identical material samples, will exceed the tabulated reproducibility R not more than once in twenty cases.
B.4.2 For a percentage difference test (value) averages: The percentage between difference two

averages, found I.+ ­ xz I betweentwo test (value) on nominally identical material samples under normal and correct operation of the test procedure, will exceed the tabulated repeatability r on average not more that once in twenty cases,
B.3.2
For a percentage difference between difference two

[14 -%1/(%

+.%)/2] x

100

between two independently measured test (value) averages, found in two laboratories using normal and
correct samples, test procedures will exceed on nominally the tabulated identical material reproducibility

test (value) averages: [Ix, -x21/(xl

The percentage x

+xJ/2]

100

(R)

not more than once in twenty

cases.

14

(Continued

from second

cover)

In case of ISO 1826:1981, ISO 3383:1985, ISO 4661-1:1993 and lSO/TR 9276:1986, the Committee, responsible for the preparation of this standard, took cognizance of these standards and decided that they are acceptable for use in conjunction with this standard. For tropical countries like India, the standard temperature 27 * 2°C and 65 * 5 percent respectively. and the relative humidity shall be taken as

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